fix(adapter.requirejs): do not configure baseUrl automatically

I believe in most cases people need to use different baseUrl anyway. This means
people need to understand that Testacular serves files under `/base/*` (which is
the basePath from the testacular.conf.js) and under `/absolute/*` (files from
outside of the project's basePath). But it's less magic and less confusing.

See #291, #292 for more info.

Closes #291